Fix directories for bug-17312.

Also add --cfg=smpi/cpu_threshold:-1 and --log=smpi_kernel.thres:warning
to the command line.
Fix parameter names.
[mc] Really fix DW_AT_high_pc for DWARF4

In DWARF4, DW_AT_high_pc can be an offset from DW_AT_low_pc instead of
a relocatable address.

MC works with DWARF4!
[mc] Correctly handle the end of the stack unwinding

unw_step returns 0 when reaching the bottom of the stack: this return
code was not handled correctly leading to infinite loops in some
cases.
[mc] Comment unhandled rangelistptr class in DW_AT_start_scope
[mc] Kernel Samepage Merging support (Linux)

Add MADV_MERGEABLE advice (madvise) for KSM in the heaps and
read/write segments: mark these regions of memory as candidate for
KSM. As the stacks are stored on the heap, they are candidate for KSM
as well.

In order to work, KSM must be enabled on the system (by root):

    # Enable:
    echo 1 > /sys/kernel/mm/ksm/run
    # Do some real work:
    echo 10000 > /sys/kernel/mm/ksm/pages_to_scan

See Documentation/vm/ksm.txt:

  https://www.kernel.org/doc/Documentation/vm/ksm.txt

We would like to only mark the .data+.bss and not the other sections
of the segment.
[mc] Fix compatibility with old/broken version of dwarf.h
[mc] Fix type of expression resolution methods (uintpt_t and not Dwarf_Off)
model-checker : smpi mutual exclusion example
[mc] Change type for type->id
replace warnings by debug messages
privatization : perform the initialization at process launch, not at MPI_Init time
Also switch at destroy time, to avoid deallocation problems in user code
[mc] Fix type conversions
[mc] Fix type conversion
[mc] Fix type conversion (once again)
[mc] Fix type conversion in unit test
forgotten useless line (should not do anything with our sets of flags for mmapped pages)
Remove benchmarking calls in MPI functions that don't actually perform comms and are not traced,
We don't need to halt processes and trigger context switches for them (and privatization switches).
This should improve SMPI performance a little.
[mc] Better fix for compatibility with old/broken version of dwarf.h.

Avoids to use a hardcoded value.
[mc] Reduce stack_size for tests mc-bugged*.

Default stack size was recently increased from 128KiB to 8MiB,
which is a bit too much on small machines (e.g. on CI).

Reduce it to 256KiB (2 times the old size) for tests mc-bugged*.